Biology: Topic-wise Test- 9 - NEET MCQ

The phenomenon of ‘red snow’ and Chlamydomonas species:
Red snow is a phenomenon commonly observed in polar regions, where the snow appears red or pink due to the presence of certain algae. One of the main contributors to this phenomenon is a species of algae called Chlamydomonas.
Identification of the Chlamydomonas species:
Among the given options, the Chlamydomonas species responsible for red snow is C. nivalis.
Reasons for choosing C. nivalis as the correct answer:
- C. nivalis is a well-known species of Chlamydomonas that is often found in polar regions.
- This species is adapted to survive in extreme cold and harsh conditions, making it suitable for inhabiting snow and ice.
- C. nivalis has a red pigmentation, which gives the characteristic red or pink color to the snow when it blooms in large numbers.
- The red pigmentation is believed to protect the algae from excessive sunlight and harmful UV radiation.
- C. nivalis is also known to produce secondary metabolites that act as antifreeze agents, helping the algae survive in freezing temperatures.
Other options:
- C. coccifera: While this species is also a type of Chlamydomonas, it is not specifically associated with the phenomenon of red snow.
- C. media and C. reticulata: These species are not commonly associated with red snow, and their pigmentation is not typically red.
In conclusion, the correct answer is A. C. nivalis, as it is the Chlamydomonas species responsible for the phenomenon of red snow in polar regions.

'Red rust of tea' is caused by parasitic
A: Cephaleuros
- Cephaleuros is a parasitic alga that causes 'red rust' disease in tea plants.
- It is a common disease that affects tea plantations worldwide.
- The alga infects the leaves and stems of the tea plant, causing rusty red or orange spots.
- These spots can spread and cover large areas of the plant, leading to reduced photosynthesis and overall plant health.
- Cephaleuros thrives in warm and humid conditions, making tea-growing regions susceptible to the disease.
- The disease can be controlled through cultural practices such as proper pruning, regular removal of infected leaves, and maintaining good airflow within the plantation.
- Fungicides can also be used to control the spread of the disease.
B: Puccinia
- Puccinia is a genus of rust fungi that primarily infects cereal crops and grasses.
- While it does not directly cause 'red rust of tea,' it is not the correct answer for the given question.
C: Mucor
- Mucor is a common mold that can be found in various environments.
- It is not known to cause 'red rust of tea,' so it is not the correct answer.
D: Fusarium
- Fusarium is a genus of fungi that can cause various plant diseases, including wilts and rots.
- While it may affect tea plants, it is not specifically associated with causing 'red rust of tea.'
Therefore, the correct answer is A: Cephaleuros as it is the parasitic alga responsible for causing 'red rust of tea.'

The pigments that are common on all algae are:
- Chlorophyll 'a': This is the primary pigment found in algae and is responsible for capturing light energy for photosynthesis. It absorbs red and blue wavelengths of light and reflects green light, giving algae their characteristic green color.
- Phycocyanin: This pigment is a type of phycobiliprotein and is commonly found in blue-green algae (cyanobacteria). It absorbs blue light and gives algae a bluish color.
- Phycoerythrin: Another phycobiliprotein pigment, phycoerythrin absorbs green light and imparts a reddish color to algae. It is commonly found in red algae and some cyanobacteria.
Explanation:
- Algae are a diverse group of photosynthetic organisms that can range from single-celled microscopic organisms to large seaweeds. They can be found in various aquatic environments, including freshwater and marine habitats.
- Algae contain different types of pigments that allow them to absorb light energy for photosynthesis. These pigments play a crucial role in capturing specific wavelengths of light and converting it into chemical energy.
- Chlorophyll 'a' is the most common pigment found in algae and is essential for photosynthesis. It absorbs light energy in the red and blue regions of the spectrum, while reflecting green light. This is why algae often appear green.
- Phycocyanin and phycoerythrin are additional pigments found in certain groups of algae. Phycocyanin is typically found in blue-green algae and absorbs blue light, giving them a bluish color. Phycoerythrin is commonly found in red algae and some cyanobacteria, absorbing green light and giving them a reddish color.
- While chlorophyll 'a' is present in all algae, the presence of phycocyanin and phycoerythrin can vary depending on the specific group or species of algae.
Therefore, the correct answer is B: Chlorophyll 'a'.

The Stellar System of Gymnosperms: Eustele
Definition:
The stellar system refers to the arrangement of vascular tissue in plants. Gymnosperms are a group of seed-producing plants that do not have flowers or fruits. The stellar system in gymnosperms is known as eustele.
Characteristics of Eustele in Gymnosperms:
- Eustele is the primary type of stellar system found in gymnosperms.
- It is a complex vascular system characterized by the presence of a solid core of xylem surrounded by phloem.
- The xylem and phloem are arranged in distinct bundles or strands.
- The xylem forms the central core or pith, while the phloem surrounds the xylem.
- The strands of xylem and phloem are arranged in a radial pattern, with alternating layers of xylem and phloem.
- The xylem conducts water and minerals from the roots to the rest of the plant, while the phloem transports sugars and other organic compounds to different parts of the plant.
- The eustele provides strength and support to the plant, allowing it to grow tall and withstand environmental stresses.
Comparison with Other Types of Stellar Systems:
- Atactostele: Atactostele is a type of stellar system found in ferns. It is characterized by the scattered arrangement of vascular tissues without a distinct core.
- Solanostele: Solanostele is a type of stellar system found in certain aquatic plants. It consists of a central core of xylem surrounded by phloem, similar to eustele.
- Siphonostele: Siphonostele is a type of stellar system found in some ferns and seed plants. It consists of a hollow cylinder of vascular tissue with a pith in the center.
Conclusion:
In conclusion, the stellar system of gymnosperms is eustele. This complex arrangement of vascular tissue provides strength and support to the plant, allowing it to grow and thrive in various environmental conditions.

Cleavage polyembryony occurs in Pinus.
Explanation:
Cleavage polyembryony is a type of polyembryony, which refers to the formation of multiple embryos from a single fertilized egg. In this process, the zygote undergoes repeated divisions to form several embryos.
Here is a detailed explanation of why cleavage polyembryony occurs in Pinus:
1. Pinus is a gymnosperm: Gymnosperms are a group of plants that bear naked seeds, meaning the seeds are not enclosed in a fruit. Pinus belongs to the gymnosperm group and is commonly known as a conifer.
2. Structure of the ovule: The ovules in Pinus are found on the scales of female cones. Each ovule consists of a single megasporangium, which contains a megaspore mother cell.
3. Formation of the female gametophyte: The megaspore mother cell undergoes meiosis to produce four haploid megaspores. Out of these, only one megaspore survives and develops into a female gametophyte.
4. Double fertilization: Pollen grains from the male cones are transferred to the female cones, and the pollen tube grows into the ovule. Two male gametes are released, one fusing with the egg cell to form the zygote and the other fusing with the polar nuclei to form the endosperm (nutritive tissue).
5. Cleavage polyembryony: In some species of Pinus, such as Pinus strobus, the zygote undergoes cleavage (repeated divisions) to form multiple embryos. These embryos can originate from both the zygote and the surrounding cells of the female gametophyte.
6. Embryo development: The embryos continue to develop within the ovule and are eventually released as mature seeds. Each seed may contain multiple embryos, which can give rise to multiple individuals upon germination.
In conclusion, cleavage polyembryony occurs in Pinus, which is a gymnosperm. This phenomenon involves the formation of multiple embryos from a single fertilized egg through repeated divisions.

Answer:
The correct answer is B: Annulus.
Explanation:
The dehiscence of the sporangium in the male shield fern (Dryopteris) is controlled by the annulus. Here is a detailed explanation:
1. Sporangium: It is a structure found in ferns that contains spores. In the male shield fern, the sporangium is responsible for producing and releasing spores.
2. Dehiscence: Dehiscence refers to the opening or splitting of a structure to release its contents. In the case of the sporangium, dehiscence occurs to release the spores.
3. Annulus: The annulus is a specialized structure found in the sporangium of many ferns. It is a ring-shaped band of cells that surrounds the sporangium.
4. Role of Annulus: The annulus plays a crucial role in the dehiscence of the sporangium. When the spores are mature and ready to be released, the cells of the annulus undergo differential drying. This leads to the contraction of the annulus cells, causing the sporangium to split open.
5. Release of Spores: Once the sporangium splits open, the spores are released into the environment. From there, they can disperse and develop into new fern plants under suitable conditions.
In conclusion, the annulus controls the dehiscence of the sporangium in the male shield fern (Dryopteris), allowing the release of spores for reproduction.

Pseudoelaters in Anthoceros:
- Pseudoelaters are specialized cells found in the sporophyte of certain mosses and liverworts.
- Anthoceros is a genus of liverworts, and it is in this genus that pseudoelaters are found.
Characteristics of Pseudoelaters:
- Pseudoelaters are elongated, tubular cells that have thickened walls.
- They are hygroscopic, meaning they can change their shape in response to changes in moisture.
- Pseudoelaters are involved in spore dispersal in liverworts.
Function of Pseudoelaters:
- During dry conditions, the pseudoelaters coil up, helping to protect the developing spores.
- When the environment becomes humid, the pseudoelaters straighten out, aiding in the dispersal of spores.
- The movement of pseudoelaters helps in the release of spores from the sporangium, increasing the chances of spore dispersal to new locations for germination.
Other Liverworts and Mosses:
- While pseudoelaters are found in Anthoceros, they are not present in the other options listed.
- Funaria is a genus of mosses, Sphagnum is a genus of peat mosses, and Marchantia is a genus of liverworts.
- These liverworts and mosses may have other mechanisms for spore dispersal, but pseudoelaters are not a characteristic feature in them.
Therefore, the correct answer is D: Anthoceros, as pseudoelaters are specifically found in this genus of liverworts.

Megasporophyll is the term used in gymnosperm to denote:
- Definition: Megasporophyll is a specialized leaf-like structure in gymnosperms that bears the megasporangia or ovules.
- Function: Megasporophylls are responsible for producing and protecting the female reproductive structures in gymnosperms.
- Location: Megasporophylls are typically found in the female cones of gymnosperms.
- Female Reproductive Structures: The megasporangia or ovules are housed within the megasporophylls and are responsible for producing the female gametophyte and ultimately the female reproductive cells.
- Carpels: Carpel is a term used in angiosperms to denote the female reproductive structure. It is not the correct term for megasporophylls in gymnosperms.
- Stamens: Stamens are the male reproductive structures in angiosperms. They are not associated with megasporophylls in gymnosperms.
- Leaves: While megasporophylls resemble leaves in appearance, they are specialized structures that serve reproductive functions in gymnosperms.
- Female Cone: The megasporophylls are indeed found in the female cone of gymnosperms, but the term "female cone" itself is not the correct term for megasporophylls.
Therefore, the correct answer is A: carpels. Megasporophylls in gymnosperms are equivalent to carpels in angiosperms.

Canada balsam is extracted from Abies.
Abies is a genus of coniferous trees in the family Pinaceae. It is commonly known as fir trees. Canada balsam is obtained from the resin of certain species of Abies trees, specifically Abies balsamea, which is native to North America.
Here is a detailed explanation of why Canada balsam is extracted from Abies:
1. Abies balsamea: The specific species of Abies tree from which Canada balsam is extracted is Abies balsamea. This tree is commonly known as the balsam fir or the Canada balsam fir.
2. Resin extraction: Canada balsam is obtained by extracting the resin from the bark of Abies balsamea trees. The resin is collected and processed to produce Canada balsam.
3. Properties: Canada balsam is a viscous and sticky resin with a pale yellow color. It has a pleasant balsamic scent. It is commonly used in various applications such as microscopy, optical equipment, and as an adhesive or sealant.
4. Historical significance: Canada balsam has been used for centuries due to its unique properties. It has been traditionally used in microscopy to mount specimens on glass slides due to its refractive index, which is close to that of glass. It also has excellent adhesive properties, making it suitable for bonding and sealing applications.
In conclusion, Canada balsam is extracted from Abies, specifically Abies balsamea, which is a species of fir tree native to North America. The resin of this tree is collected and processed to produce Canada balsam, which is used for various purposes such as microscopy and adhesive applications.

The plant nearest to angiosperm is Gnetum.
Explanation:
- Angiosperms are flowering plants that produce seeds enclosed in a protective fruit.
- Gnetum is a genus of gymnosperms that are the closest relatives to angiosperms.
- Gymnosperms are a group of seed-producing plants that include conifers, cycads, and ginkgo.
- Among the given options, Gnetum is the only gymnosperm genus, making it the closest to angiosperms.
- Taxus is a genus of conifers, which are also gymnosperms, but they are not as closely related to angiosperms as Gnetum.
- Cycas is a genus of cycads, another group of gymnosperms, but they are not as closely related to angiosperms as Gnetum.
- Pinus is also a genus of conifers, but they are not as closely related to angiosperms as Gnetum.
- Therefore, the correct answer is A: Gnetum.

Explanation:
Iodine and bromine are both extracted from specific sources in nature. Here is a detailed explanation of where these elements are extracted from:
Laminaria:
- Laminaria is a type of brown seaweed commonly found in cold-water environments.
- It is a rich source of iodine and is used as a primary source for iodine extraction.
Rhodymenia:
- Rhodymenia is another type of red seaweed that is also used for iodine extraction.
- It contains iodine compounds that can be processed to obtain iodine.
Therefore, iodine is primarily extracted from Laminaria and Rhodymenia seaweeds.
It is important to note that bromine is not directly extracted from any specific plant or seaweed. Instead, it is obtained as a byproduct of saltwater evaporation. The extraction process involves the following steps:
1. Saltwater evaporation: Saltwater is collected in large shallow ponds and left to evaporate under the sun.
2. Crystallization: As the water evaporates, salt crystals begin to form. These crystals contain various salts, including bromide salts.
3. Bromine extraction: Once the salt crystals are formed, they are collected and processed to extract bromine. This involves treating the crystals with chlorine gas, which reacts with the bromide salts to form bromine gas. The bromine gas is then collected and purified.
In conclusion, iodine is primarily extracted from Laminaria and Rhodymenia seaweeds, while bromine is obtained as a byproduct of saltwater evaporation.

Zygotic Meiosis occurs in the Haplontic life cycle.
Explanation:
- The Haplontic life cycle is a type of life cycle that is characterized by the dominance of the haploid phase of the organism's life.
- In this life cycle, the organism spends most of its life in the haploid form.
- Zygotic Meiosis, also known as gametic meiosis, is a type of meiosis that occurs in the zygote stage of the life cycle.
- During zygotic meiosis, the zygote undergoes meiosis to produce haploid cells called gametes.
- These gametes then fuse with other gametes to form a diploid zygote, starting the cycle again.
- Zygotic Meiosis is commonly found in algae, fungi, and some protists.
- It is an important part of their life cycle as it allows for genetic variation and the production of offspring with different genetic combinations.
In conclusion, Zygotic Meiosis occurs in the Haplontic life cycle, which is characterized by the dominance of the haploid phase of the organism's life.

Answer:
The gametes in Spirogyra (lateral conjugation) are morphologically similar but physiologically dissimilar.
Explanation:
Morphological Similarity:
- The gametes in Spirogyra are structurally similar in size and shape.
- They are both small and biflagellate, meaning they have two flagella.
Physiological Dissimilarity:
- Despite their morphological similarity, the gametes in Spirogyra have different physiological functions.
- The gamete that is produced by the "+" filament is male and is called the "+" gamete. It is small and mobile, actively swimming towards the "-" gamete.
- The gamete that is produced by the "-" filament is female and is called the "-" gamete. It is larger and stationary, waiting for the "+" gamete to reach it.
Overall, while the gametes in Spirogyra may look similar in shape and size, they have distinct physiological roles and behaviors.

Explanation:
The correct pair among the options is B: Spirogyra - Amoeboid gametes.
Here is a detailed explanation for each option:
A: Batrachospermum - Kelps
- Batrachospermum is a genus of freshwater red algae.
- Kelps, on the other hand, are large brown algae found in marine environments.
- Batrachospermum and kelps belong to different taxonomic groups, so this pair is incorrect.
B: Spirogyra - Amoeboid gametes
- Spirogyra is a genus of filamentous green algae commonly found in freshwater habitats.
- Amoeboid gametes are a type of reproductive cells that can move and change shape like amoebas.
- Spirogyra does produce amoeboid gametes during its sexual reproduction, so this pair is correct.
C: Gracilaria - Red tide
- Gracilaria is a genus of red seaweed commonly found in marine environments.
- Red tide, on the other hand, refers to a phenomenon caused by the rapid growth of certain species of algae, including dinoflagellates, which produce toxins that discolor the water.
- Gracilaria is not directly associated with red tide, so this pair is incorrect.
D: Chlamydomonas - Heterokont
- Chlamydomonas is a genus of unicellular green algae commonly found in freshwater and soil environments.
- Heterokont, on the other hand, refers to a group of algae that possess two different types of flagella.
- Chlamydomonas is a member of the Chlorophyta group and does not have heterokont characteristics, so this pair is incorrect.
In conclusion, the correct pair is B: Spirogyra - Amoeboid gametes.

The Tracheophyta is a division of plants that includes vascular plants with specialized tissues for the transport of water and nutrients. It is also known as the vascular plants division. Here is a detailed explanation of the answer:
Tracheophyta includes:
1. Pteridophyta:
- Pteridophyta refers to the ferns and fern allies.
- They have true roots, stems, and leaves.
- They reproduce by spores.
2. Spermatophyta:
- Spermatophyta refers to the seed-bearing plants.
- They have true roots, stems, and leaves.
- They reproduce by seeds.
Therefore, the correct answer is D: Pteridophyta and spermatophyta, as they are the two main groups of plants included in the Tracheophyta division.

The wing of the seed of Pinus is an outgrowth of the integument and an outgrowth of the ovuliferous scale.
Explanation:
The seed of Pinus, commonly known as a pine seed, has a unique feature called the wing. This wing is an important adaptation that aids in the dispersal of the seed. Let's break down the options and understand why the correct answer is D.
A: An outgrowth of the integument
- The integument is the outer layer of the ovule, which eventually develops into the seed coat.
- In Pinus, the wing of the seed is derived from the integument, specifically from the outer layer.
- This wing-like structure helps in the wind dispersal of the seed.
B: An outgrowth of the ovuliferous scale
- The ovuliferous scale is a modified leaf structure found in the cones of Pinus.
- It bears the ovules, which eventually develop into seeds.
- The wing of the seed in Pinus is also an outgrowth of the ovuliferous scale.
- The scale and the integument work together to form the winged structure.
C: An outgrowth of the fruit
- In Pinus, the cone is the reproductive structure that contains the seeds.
- The cone is not considered a true fruit, as it lacks the characteristics of a typical fruit.
- Therefore, the wing of the seed is not an outgrowth of the fruit itself.
D: Both 1. and 2.
- The correct answer is D because the wing of the seed in Pinus is indeed an outgrowth of both the integument and the ovuliferous scale.
- The integument contributes to the development of the wing, while the ovuliferous scale provides the necessary support.
In conclusion, the wing of the seed in Pinus is formed by the combined efforts of the integument and the ovuliferous scale. This special adaptation allows for efficient seed dispersal through wind.

To determine the number of chromosomes in the spore of a fern embryo, we need to understand the process of fern reproduction and the role of chromosomes in this process.
1. Fern Reproduction:
- Ferns reproduce through a process called alternation of generations, which involves both sexual and asexual reproduction.
- The fern life cycle consists of two distinct stages: the sporophyte and the gametophyte.
- The sporophyte is the familiar leafy fern plant, while the gametophyte is a small, independent structure.
- Sporophytes produce spores through meiosis, and these spores develop into gametophytes.
- Gametophytes produce gametes (sperm and eggs) through mitosis, and fertilization between gametes leads to the formation of a new sporophyte.
2. Chromosome Count:
- In ferns, the sporophyte is diploid, meaning it has two sets of chromosomes (2n).
- The gametophyte, on the other hand, is haploid, meaning it has only one set of chromosomes (n).
- During meiosis in the sporophyte, the chromosome number is halved, resulting in the formation of haploid spores.
3. Calculation:
- Given that the number of chromosomes in the foot of the fern embryo is 8 (2n), we can determine the number of chromosomes in its spore.
- Since spores are produced through meiosis, which reduces the chromosome count by half, the number of chromosomes in the spore would be half of the number in the foot of the fern embryo.
- Therefore, the number of chromosomes in the spore would be 8/2 = 4 (n).
Conclusion:
The number of chromosomes in the spore of a fern embryo would be 4 (n). Hence, option A is the correct answer.

Funaria hygrometica gametophyte is Monoecious or Dioecious
The correct answer is B: Monoecious or dioecious.
Explanation:
Funaria hygrometica is a common moss species that exhibits sexual reproduction. In mosses, the gametophyte generation is the dominant phase, and it produces both male and female reproductive structures.
Here is a detailed explanation to support the answer:
1. Moss life cycle:
- Mosses have a life cycle that alternates between a haploid gametophyte stage and a diploid sporophyte stage.
- The gametophyte is the dominant phase and carries out most of the plant functions, including sexual reproduction.
- The sporophyte is a small structure that grows on the gametophyte and produces spores.
2. Sexual reproduction in mosses:
- Mosses reproduce sexually by the fusion of gametes produced by male and female gametangia.
- The male gametangia, called antheridia, produce sperm cells.
- The female gametangia, called archegonia, produce egg cells.
3. Monoecious and dioecious plants:
- Monoecious plants have separate male and female reproductive structures on the same individual plant.
- Dioecious plants have separate male and female reproductive structures on different individual plants.
4. Funaria hygrometica gametophyte:
- Funaria hygrometica gametophyte can exhibit both monoecious and dioecious characteristics.
- Some individuals of Funaria hygrometica have both male and female reproductive structures on the same gametophyte plant (monoecious).
- Other individuals have distinct male and female gametophytes, with male plants producing only antheridia and female plants producing only archegonia (dioecious).
In conclusion, Funaria hygrometica gametophyte can be monoecious or dioecious, depending on the individual plant. Some plants have both male and female structures on the same plant (monoecious), while others have separate male and female plants (dioecious).

Scalariform Conjugation in Spirogyra:
Scalariform conjugation is a type of sexual reproduction that occurs in filamentous green algae called Spirogyra. In this process, two morphologically dissimilar gametes fuse to form a zygote. Let's explore this in detail:
Morphological Differences:
Scalariform conjugation involves the fusion of two gametes that are morphologically dissimilar. This means that they have distinct physical characteristics. The two gametes involved in scalariform conjugation are:
1. Male Gamete (Antherozoid): The male gamete, also known as an antherozoid, is a small and motile structure. It is elongated with a single flagellum, which helps in its movement.
2. Female Gamete (Oogonium): The female gamete, called an oogonium, is relatively larger and stationary. It is spherical or oval-shaped and contains a single large non-motile egg.
Physiological Differences:
In addition to morphological dissimilarity, the gametes involved in scalariform conjugation are also physiologically different. These physiological differences are related to their roles in the process of fertilization:
1. Male Gamete (Antherozoid): The antherozoid is specialized for motility and is equipped with a flagellum. It is responsible for swimming towards the female gamete for fertilization.
2. Female Gamete (Oogonium): The oogonium, on the other hand, does not possess any motility. It remains stationary and provides the egg for fertilization.
Summary:
In scalariform conjugation of Spirogyra, the fusing gametes are morphologically dissimilar. The male gamete (antherozoid) is small, motile, and possesses a flagellum, while the female gamete (oogonium) is relatively larger and non-motile. These morphological and physiological differences ensure successful fertilization and the formation of a zygote in Spirogyra.

Explanation:
Thallophytes:
- Thallophytes are a group of plants that lack true stems, leaves, and roots. They include organisms like algae, fungi, and lichens.
- Thallophytes reproduce through various methods, including the formation of gametes.
Gametes in Thallophytes:
- Gametes are reproductive cells, either male (sperm) or female (egg), that are involved in sexual reproduction.
- In some thallophytes, the gametes can behave directly as zygospores without undergoing fusion.
Azygospores:
- Azygospores are reproductive bodies that are formed directly from gametes without fusion.
- These azygospores can develop into new individuals without the need for fertilization.
In the given options:
- Option A: Zygospores are not the correct answer because zygospores are the result of fusion between two gametes.
- Option B: Aplanospores are not the correct answer because aplanospores are a type of spore produced by certain algae and fungi during asexual reproduction.
- Option C: Hypnospores are not the correct answer because hypnospores are a type of resting spore formed by certain algae and fungi in unfavorable conditions.
- Option D: Azygospores are the correct answer because they are reproductive bodies that are formed directly from gametes without fusion.
Therefore, the correct answer is D: Azygospores.

The number of chloroplasts in a cell of Spirogyra is D: One to fourteen.
Explanation:
Spirogyra is a filamentous green algae that belongs to the division Chlorophyta. It is known for its spiral-shaped chloroplasts, which are the organelles responsible for photosynthesis. The number of chloroplasts in a cell of Spirogyra can vary depending on various factors such as the species, the stage of the cell cycle, and environmental conditions. Here is a detailed explanation:
- Chloroplasts in Spirogyra: Spirogyra cells contain a characteristic spiral arrangement of chloroplasts, which gives them their name. These chloroplasts are elongated, ribbon-like structures that run along the length of the cell.
- Variability in chloroplast number: The number of chloroplasts in a Spirogyra cell can vary. It is generally observed that a single Spirogyra cell contains anywhere between one to fourteen chloroplasts. The exact number depends on factors such as the size of the cell, the age of the cell, and the metabolic activity of the cell.
- Factors influencing chloroplast number: The number of chloroplasts in a Spirogyra cell can change dynamically. For example, during the process of cell division, the chloroplasts replicate and distribute evenly between the daughter cells. This results in an increase in the total number of chloroplasts in the organism.
- Environmental conditions: Environmental conditions can also influence the number of chloroplasts in Spirogyra cells. Factors such as light intensity, nutrient availability, and temperature can affect the growth and development of chloroplasts. In optimal conditions, Spirogyra cells may have a higher number of chloroplasts compared to unfavorable conditions.
In conclusion, the number of chloroplasts in a cell of Spirogyra can vary from one to fourteen, depending on factors such as species, cell cycle stage, and environmental conditions.

Paraphyses of Male Branch of Funaria
The paraphyses of the male branch of Funaria are few celled with terminal cells globose.
Explanation:
- Paraphyses are sterile filaments found among the reproductive structures of mosses.
- In the male branch of Funaria, the paraphyses have the following characteristics:
- They are few celled, meaning they consist of only a few cells.
- The terminal cells of the paraphyses are globose in shape, which means they are round or spherical.
- The function of the paraphyses in the male branch of Funaria is to provide support and protection to the male reproductive structures called antheridia.
- The antheridia produce sperm cells that are released into the environment to fertilize the female reproductive structures of the moss.
- The paraphyses help in the dispersal of the sperm cells and protect them from desiccation or damage.
- The globose shape of the terminal cells of the paraphyses may aid in the efficient dispersal of sperm cells.
- Overall, the paraphyses play an important role in the reproductive process of Funaria by facilitating the successful fertilization of the female gametes.

Answer:
The group of plants that shows both the origin and evolution of the sporophyte is Pteridophytes.
Explanation:
1. Thallophytes:
- Thallophytes, such as algae and fungi, do not have a well-developed sporophyte generation. They primarily rely on the gametophyte generation for reproduction.
2. Bryophytes:
- Bryophytes, including mosses and liverworts, have a dominant gametophyte generation and a reduced sporophyte generation.
- The sporophyte in bryophytes is dependent on the gametophyte for nutrition and support.
3. Pteridophytes:
- Pteridophytes, which include ferns and horsetails, exhibit a gradual elaboration of the sporophyte generation.
- The sporophyte generation in pteridophytes is independent and more elaborate compared to bryophytes.
- Pteridophytes have well-developed vascular tissues, including roots, stems, and leaves, which allow them to grow taller and have a more complex structure.
4. Gymnosperms:
- Gymnosperms, like conifers and cycads, further continue the evolution of the sporophyte generation.
- Gymnosperms have evolved seeds, which protect and nourish the developing sporophyte embryo.
Therefore, out of the given options, the group of plants that shows both the origin and evolution of the sporophyte is Pteridophytes.

Answer: C. Multiciliate and sickle shaped
Explanation:
The antherozoids of Dryopteris are multiciliate and sickle-shaped. Here is a detailed explanation of each term:
1. Multiciliate:
- Antherozoids are male gametes (sperm cells) in ferns that are responsible for fertilization.
- The term "multiciliate" refers to the presence of multiple cilia or flagella on the antherozoids.
- Cilia are hair-like structures that help in the movement of antherozoids towards the egg for fertilization.
- The presence of multiple cilia allows for more efficient movement and increases the chances of successful fertilization.
2. Sickle-shaped:
- The term "sickle-shaped" describes the overall shape of the antherozoids.
- Antherozoids of Dryopteris have a curved or sickle-like shape.
- This shape is advantageous for navigating through the water environment and reaching the egg.
- The curved shape allows for better movement and enhances the chances of successful fertilization.
Therefore, the antherozoids of Dryopteris are multiciliate and sickle-shaped, which aids in their movement and fertilization.

Reduction division in Selaginella occurs during the formation of both microspores and megaspores.
Explanation:
Selaginella is a genus of plants that belong to the family Selaginellaceae. Reduction division, also known as meiosis, is a type of cell division that results in the formation of gametes or spores with half the number of chromosomes as the parent cell.
- Reduction division occurs during the formation of both microspores and megaspores in Selaginella.
- Microspores are haploid spores that give rise to male gametophytes, which produce sperm cells.
- Megaspores are also haploid spores that give rise to female gametophytes, which produce egg cells.
- During reduction division, the diploid cells in the sporophyte undergo meiosis to produce haploid microspores and megaspores.
- These spores then develop into gametophytes, which are the reproductive structures of the plant.
- In the case of Selaginella, both microspores and megaspores are formed through reduction division, indicating that it occurs during the formation of both male and female reproductive structures.
- This process is essential for sexual reproduction in Selaginella and ensures genetic diversity in the offspring.
Therefore, the correct answer is B: During the formation of both microspores and megaspores.

The most primitive pteridophyte among the following is Psilotum:
Explanation:
What are pteridophytes?
- Pteridophytes are a group of plants that reproduce and disperse through spores.
- They do not produce flowers or seeds and are considered to be primitive plants.
Comparing the given options:
- Psilotum, Dryopteris, Selaginella, and Lycopodium are all examples of pteridophytes.
- Among these options, Psilotum is the most primitive pteridophyte.
Characteristics of Psilotum:
- Psilotum, commonly known as whisk fern, is a genus of fern-like plants.
- It is considered to be one of the most primitive living vascular plants.
- Psilotum lacks true roots, leaves, and well-developed vascular tissues.
- It has simple, dichotomously branching stems.
- The reproductive structures of Psilotum are also simple and resemble those of early land plants.
Comparing with other options:
- Dryopteris, Selaginella, and Lycopodium are more advanced pteridophytes compared to Psilotum.
- Dryopteris is a fern genus with well-developed leaves, roots, and vascular tissues.
- Selaginella is a genus of spikemosses that has true roots, leaves, and well-developed vascular tissues.
- Lycopodium, commonly known as clubmoss, also has true roots, leaves, and well-developed vascular tissues.
Conclusion:
- Psilotum is the most primitive pteridophyte among the given options.
- It lacks true roots, leaves, and well-developed vascular tissues, making it closer to the characteristics of early land plants.

Pinus Seeds and Cotyledons
Introduction:
Pinus is a genus of coniferous trees that produce seeds known as pine seeds. These seeds are enclosed within the female cone and are important for the reproduction and propagation of pine trees. The cotyledons, also known as seed leaves, are the embryonic structures present in the seeds that provide nutrients to the developing seedling.
Explanation:
Pinus seeds have a unique characteristic when it comes to cotyledons. Here's a detailed explanation:
1. Cotyledons:
Cotyledons are the first leaves that emerge from a germinating seed. They provide energy and nutrients to the developing seedling until it can produce its own food through photosynthesis. In the case of Pinus seeds, they have a distinct cotyledon arrangement.
2. Two Cotyledons:
Pinus seeds typically have two cotyledons. These cotyledons are thin and elongated structures that store reserves of food for the growing seedling. They are usually green in color and play a vital role in the early stages of seed germination.
Conclusion:
In conclusion, Pinus seeds have two cotyledons. These cotyledons are responsible for providing the necessary nutrients and energy for the initial growth and development of the seedling. Understanding the cotyledon arrangement is crucial for studying the life cycle and reproductive strategies of pine trees.

Explanation for the excurrent habit of a Pinus tree:
A: The effect of auxin on growth of stem tip:
- Auxin is a plant hormone that promotes apical dominance, meaning it inhibits the growth of lateral branches.
- In Pinus trees, the apical meristem (the growing tip of the stem) continues to grow and elongate, while the lateral branches remain suppressed.
- This results in a straight, single main trunk with minimal branching, characteristic of the excurrent habit.
B: Competition between adjacent trees for sunlight:
- While competition for sunlight can influence tree growth, it is not the primary factor determining the excurrent habit in Pinus trees.
- Even in the absence of neighboring trees, Pinus trees still exhibit the excurrent habit.
C: Efficiency of water transport:
- While water transport efficiency is important for tree growth, it is not directly related to the excurrent habit.
- The excurrent habit of Pinus trees is primarily driven by hormonal factors and growth patterns.
D: Adaptation for wind pollination:
- Wind pollination does not directly influence the excurrent habit of Pinus trees.
- The excurrent habit primarily facilitates efficient vertical growth, allowing for better dispersal of pollen by wind.
Conclusion:
The best explanation for the excurrent habit of a Pinus tree is the effect of auxin on the growth of the stem tip. Auxin promotes apical dominance, resulting in a straight, single main trunk with minimal branching. This growth pattern is characteristic of the excurrent habit observed in Pinus trees.

The plant group that produces spores and embryo but lacks vascular tissues and seeds is:
Bryophyta
Explanation:
Bryophyta, commonly known as mosses, are a group of plants that exhibit certain characteristics. Here's a detailed explanation of why Bryophyta is the correct answer:
Spore Production:
- Bryophyta plants reproduce using spores. Spores are tiny reproductive units that are dispersed and germinate into new plants.
Embryo Production:
- Bryophyta plants also produce embryos. An embryo is a young multicellular organism that develops from a fertilized egg and is capable of growing into a new individual.
Lack of Vascular Tissues:
- Unlike vascular plants, such as Pteridophyta (ferns) and seed plants, Bryophyta lacks specialized tissues for the long-distance transport of water, nutrients, and sugars. As a result, Bryophyta plants are typically small in size and grow close to the ground.
Lack of Seeds:
- Bryophyta plants do not produce seeds. Seeds are structures that contain embryos and are capable of developing into new plants under suitable conditions.
Therefore, based on the characteristics described above, the plant group that produces spores and embryo but lacks vascular tissues and seeds is Bryophyta.

The hair-like structures covering young fern leaves and rhizome are called ramenta.
Explanation:
- Ramenta: Ramenta are small, hair-like structures that cover the surface of young fern leaves and rhizomes.
- Ramenta are mainly found in ferns and serve various functions such as protection, defense, and water absorption.
- These structures are composed of dead cells and are often formed by the disintegration of scales or glandular hairs.
- Ramenta have a variety of shapes and sizes, ranging from short and rigid to long and flexible.
- They can be found on the upper and lower surfaces of fern leaves, as well as on the surface of the rhizome.
- Ramenta play a role in protecting the young fern leaves and rhizomes from herbivores, pathogens, and excessive water loss.
- They also aid in the absorption of water and nutrients from the environment.
- The presence of ramenta can be observed by examining the surface of young fern leaves and rhizomes under a microscope or by touch.
Therefore, the correct answer is D. Ramenta.